The spring biased pivots for use on self-closing door structures such as on food service counter gates, bathroom stall doors and the like are well known. One such spring biased pivot assembly has been marketed by a number of years by Bommer Industries, Inc. having a place of business in Landrum S.C. Such pivot assemblies operate by translating the movement of the door structure to axial rotation of a cover operatively connected to one end of a helical spring relative to an elongated spindle element operatively connected to an opposing end of the helical spring. The relative rotation tightens the spring as the door structure is displaced from its initial position. The biasing force by the spring causes the door structure to swing back to its initial starting position when the force causing the initial displacement is removed. By way of example, in a typical environment of use such as in a food service counter the user may open a gate by pushing or pulling on the gate thereby causing displacement from its original position. This displacement, in turn, is translated to a cover portion of the attached pivot thereby tightening a spring housed within the structure. When the user releases the gate, the displacement force is eliminated and the spring attempts to release the stored energy thereby imparting a recuperating biasing force to the displaced gate. As the tension within the spring is released, the gate swings back towards its starting position.
One recurring problem that has been encountered during the manufacture and use of prior spring biased pivot structures has been in achieving a consistent return of the gate or door being acted upon to the desired starting position. In particular, in order to assemble a spring biased pivot, a certain degree of tolerance is required between the interacting components. In the absence of applied tension to the spring, after assembly these elements may move slightly relative to one another when the door structure is not being acted upon. This slack or play between the components may allow the door structure to engage in a degree of drift away from the desired starting position. While such drift may be relatively slight at the side of the door structure adjacent the pivot, such rotational movement is magnified at the free end of the door structure which may be several feet away. Thus a drift at the pivot of even a few degrees may cause a relatively substantial displacement of the supported door structure. Moreover, over time the spring tension may be slightly reduced such that the return force is diminished thereby imparting additional inconsistency to the return performance.
In order to address the issue of consistent return of the supported door structure to a fixed defined position, a system has been utilized to maintain the biasing spring in constant tension by blocking axial rotation of the covering elements prior to complete spring recovery as the door structure is returning to its fixed position. This blocking has been carried out by using a bottom cover having a downwardly projecting blocking shoulder that engages a static pin inserted into a radial opening in the spring engaging tensioning collar. While such a system works and has been utilized for many years, substantial skill is required to achieve the required alignment of components such that the appropriate biasing force is preloaded upon initial assembly. However, even when the initial assembly is satisfactory, during use the change in spring character may still give rise to an undesirable degree of drift. In this event there is no usable mechanism to re-tension the biasing spring.